Anti‐inflammatory activities of natural cyclopeptide RA‐XII in colitis‐associated colon cancer mouse model and its effect on gut microbiome

Colorectal cancer (CRC), the third most common cancer globally, is associated with intestinal inflammation that leads to poor prognosis. RA-XII, a natural cyclopeptide, has previously been reported to possess anti-tumor activities. Here, the anti-inflammatory activities of RA-XII were investigated in colitis-associated colon cancer mice and a co-culture in vitro model, in which colon cancer cells HCT116 and macrophages RAW264.7 were grown together to mimic the inflammatory microenvironment of CRC. Changes of inflammatory-related molecules and protein expressions in cells were evaluated after RA-XII incubation. Besides, azoxymethane and dextran sulfate sodium-induced colitis-associated colon cancer mice were treated with RA-XII for 24 days, inflammatory parameters and gut microbiome alterations were studied. Our results showed that RA-XII reversed the inflammatory responses of RAW264.7 cells induced by LPS and modulated the protein expressions of AKT, STAT3/p-STAT3, P70S6K, NF-κB and GSK3β and suppressed the expression of LC3A/B in HCT116 cells in co-culture system. RA-XII treatment restored the colitis damage in colon, reduced colon tumors numbers and decreased inflammatory factors (IL-6, IL-10 and TNF-α). The role of RA-XII on regulating gut microbiome was also demonstrated for the first time. In conclusion, our findings provided new scientific evidence for developing RA-XII as a potent anti-inflammatory agent for CRC.